This invention relates to a new oxidation process, using metal nitro or nitrosyl complexes to transfer oxygen to a substrate. Especially the invention relates to oxidation using cobalt as the metal and molecular oxygen as the oxygen source.
Cobalt nitro complexes obtained by air oxidation of the nitrosyl complexes in presence of a nitrogen or phosphorus base are known (Inorganic Chemistry, volume 12 of 1973, pages 1528-1534); but no process has heretofore been proposed, so far as we are aware, wherein such complexes function to bring about the oxidation of a substrate.
In the prior art certain oxidation processes using molecular oxygen as the oxygen source are known. In general such processes operate by adsorption on metal oxide catalyst from vapor phase; or proceed in vapor phase or liquid phase by a pathway involving peroxide and free radicals. Such reactions may not be selective for oxidation of particular structures to particular products and/or may not be broadly applicable to a given chemical class of compounds.
Prior to the filing of this application, chemically catalyzed electrochemical oxidation has been disclosed in presence of ruthenium nitro complex and aqueous base, whereby the net effect is to neutralize the base and oxidize a substrate. (J.A.C.S. 99:14/July 6, 1977--Keene et al.)
Also disclosed is production of metal nitrito compounds wherein at least one nitrito group is covalently bonded through the oxygen atom to at least one metal atom. Such compounds, e.g., those with iron or copper, are shown to catalyze oxidation of molecules such as methane or propane to the corresponding primary alcohol, and propylene to propylene oxide (U.S. Pat. No. 3,989,801 of Nov. 2, 1976 to B. O. Field et al.).